But what truly sets Long Island apart is its claim to fame as the home of Dean's Blue Hole — one of the deepest blue holes in the world and the site of an annual freediving competition.

A water-filled natural limestone cavern, Dean's Blue Hole plunges 663 feet below ground level on Long Island, part of a string of Bahamian islands south of Nassau and New Providence Island.

Researchers think that other marine sinkholes, like Dragon Hole in South China Sea, and Dean's Blue Hole in the Bahamas probably formed the same way. As the scientists continued down the hole ...

The Sansha Yongle Blue Hole is almost 1,000 feet deep, breaking the previous record of Dean’s Blue Hole in the Bahamas. Video courtesy of Reuters Follow TI: On Facebook More from Tech Scientists ...

The world's deepest salt water blue hole, that we know of, is the Dean's Blue Hole in the Bahamas which plunges to a 663 foot depth. Professor Yang Zuosheng of the Ocean University of China ...